Geosystems and Geoenvironment最新文献

{"title":"Biostratigraphy, stratigraphy and paleoenvironments of middle Eocene – middle Oligocene sediments from Onshore Niger Delta, Nigeria: Insights from foraminifera and palynomorphs","authors":"Moshood Adegboyega Olayiwola ,&nbsp;Olugbenga Temitope Fajemila","doi":"10.1016/j.geogeo.2025.100391","DOIUrl":"10.1016/j.geogeo.2025.100391","url":null,"abstract":"<div><div>In recent times, biostratigraphy, apart from its primary roles in age dating, paleoenvironmental reconstruction and correlation now constitutes a significant aspect of sequence stratigraphy applicable in exploration and production activities. Unfortunately, published biostratigraphic and biochronostratigraphic records of Niger Delta Eocene –Oligocene sediments are scanty. This integrated study of the H1-P well (1250–3931 m) from the Central Niger Delta revealed two lithostratigraphic units, the continental Benin Formation (1250–2384 m) and the Upper Agbada Formation (2384–3931 m) composed of alternating sand and shale intervals. The uppermost section (1250–2384 m), which is within the continental Benin Formation was barren of foraminifera. However, it was dated Early to Middle Oligocene (P520-P560) based on diagnostic palynomorphs. Conversely, the lowermost part (3931–2384 m), consisting moderate numbers of foraminifera species, was dated Late Eocene (P480). The paleoenvironments, which fluctuated between Coastal Deltaic to Middle Neritic, were subdivided into four highstand and four transgressive systems tracts. The 39.4 Ma, 38.0Ma, 36.8 Ma and 35.9 Ma maximum flooding surfaces, and three sequence boundaries were inferred. The youngest maximum flooding surface dated 35.9 Ma at 2385 m, was defined by the FDO <em>Nonion oyae</em>, FDO <em>Brizalina ihuoensis</em> (2402 m), presence of <em>Globigerina yeguaensis</em> and FDO <em>Uvigerinella sparsicostata</em> at 2713 m, the FDO of the diagnostic palynomorphs <em>Grimsdalea polygonalis, Doualaidites laevigatus,</em> at 2414 m / 2792 m respectively indicated the penetration of Late Eocene. The FDO <em>Uvigerina hourqi</em> delineated the Middle/Late Eocene boundary at 3121 m. The Middle Eocene is further characterized by Acme <em>Uvigerinella sparsicostata</em> and occurrence of <em>Chiloguembelina martini</em>. The sequence stratigraphic interpretation permitted age dating of the maximum flooding surfaces and the sequence boundaries within the well section.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 3","pages":"Article 100391"},"PeriodicalIF":0.0,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143843885","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Prioritization of the Tassaoute Watershed (Morocco) for soil erosion using analytical hierarchy process (AHP) and geospatial techniques","authors":"Khalid Ziadi ,&nbsp;Ahmed Barakat ,&nbsp;Abdenbi El Aloui ,&nbsp;Mustapha Ouayah ,&nbsp;Mustapha Namous","doi":"10.1016/j.geogeo.2025.100389","DOIUrl":"10.1016/j.geogeo.2025.100389","url":null,"abstract":"<div><div>Identifying areas vulnerable to soil erosion is essential for the sustainable management of natural resources and the implementation of effective prevention strategies. This study proposes a robust multi-criteria decision analysis (MCDA)framework integrated with geographic information system (GIS) technology to evaluate susceptibility to water erosion in the upstream watershed of Tassaoute (Central High Atlas, Morocco). Elevation, slope, SPI, TWI, NDVI, LULC, lithology, rainfall, distance from river, and drainage density were the ten factors we employed to establish the soil erosion vulnerability map. Criteria weights were measured using the AHP method based on suggestions from different studies and research that ensured an effective way of soil erosion control. The final susceptibility map, created from GIS data and a classification of natural phenomena, identified five distinct levels: very low, low, moderate, high and very high. It reveals a significant erosion threat, with around 60 % of the study area showing moderate to very high levels of erosion. On the other hand, 40 % of the area studied is considered to be at low risk of erosion. Areas at high risk of erosion are more common on steep slopes, with high rainfall and rocks of the marl and clay formation. The accuracy of the results is assessed using the ROC (receiver operating characteristic) curve. The area under the curve (AUC) is 0.782, equivalent to a prediction accuracy of 78.2 %. In conclusion, this model is proving to be a valuable tool for effectively guiding future planning with regard to sustainable soil and water management, in particular by addressing the problem of soil erosion.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 2","pages":"Article 100389"},"PeriodicalIF":0.0,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143825344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Holocene climate variability deciphered from Chilika Lagoon sediments: Implication for anthropogenic activity or paleocyclones?","authors":"Barnita Banerjee ,&nbsp;Monalisa Mallick ,&nbsp;Mohd Amir ,&nbsp;Abdul Hameed ,&nbsp;Luan Ozelim ,&nbsp;Nihar Ranjan Kar ,&nbsp;E.V.S.S.K. Babu ,&nbsp;K. Venkatesham ,&nbsp;M. Venkateshwarlu ,&nbsp;Tanveer Hassan ,&nbsp;Vireswar Samanta ,&nbsp;Prem Chand Kisku ,&nbsp;Debajyoti Paul ,&nbsp;Pankaj Kumar ,&nbsp;Aurovinda Panda","doi":"10.1016/j.geogeo.2025.100390","DOIUrl":"10.1016/j.geogeo.2025.100390","url":null,"abstract":"<div><div>Coastal lagoons, acting as a link between land and sea, serve as valuable archives for past climate variations, human activities, and paleo-cyclonic events. In this study, we employ a multi-proxy approach to analyze sedimentary records and uncover climatic shifts influenced by both monsoonal and non-monsoonal factors. Our analysis incorporates sediment characteristics such as grain size, magnetic susceptibility (MS), and clay mineralogy to infer high-energy conditions within the Chilika Lagoon. Additionally, we utilize Rock-Eval pyrolysis and deconvolution of flame ionization detector (FID) signals to determine the type of organic matter (OM) present.</div><div>Findings reveal that during the Early Holocene, a high sand percentage and elevated MS indicate an intensified monsoon, coinciding with a dominance of terrestrial OM. However, as monsoonal intensity declined after the Early Holocene, marine OM became more prevalent, likely linked to the formation of an estuary around ∼7.7 Ka. Despite a weakening monsoon around ∼4 Ka, MS values remained high, possibly due to increased aeolian input, which transported titanomagnetite, contributing to elevated MS in the sediment record. After ∼4 Ka, the sedimentary record indicates a greater influx of terrestrial OM, likely due to the formation of a barrier spit that limited marine influence. From this period onward, monsoonal intensity gradually increased, peaking around ∼1.1 Ka, coinciding with the Medieval Warm Period. Following ∼1.1 Ka, sedimentation rates rose, accompanied by low magnetic susceptibility (MS) and high sand content. This phase also shows an increase in both terrestrial and marine OM, along with higher CaCO₃ and illite concentrations, suggesting the impact of high-energy events, possibly cyclones. The intensification of cyclonic activity after ∼1.1 Ka may be associated with a weakening of El Niño–Southern Oscillation (ENSO) intensity during this period.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 3","pages":"Article 100390"},"PeriodicalIF":0.0,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143852121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"WebGIS-based decision support system for soil erosion risk assessment for Guder River catchment, Ethiopia","authors":"Kedir Kemal Hajisheko ,&nbsp;Karuturi Venkata Suryabhagavan ,&nbsp;Karuturi Soumya","doi":"10.1016/j.geogeo.2025.100387","DOIUrl":"10.1016/j.geogeo.2025.100387","url":null,"abstract":"<div><div>Soil erosion is a crucial environmental issue affecting agricultural productivity, water quality, and ecosystem sustainability. Deforestation and human activities have led to excessive soil erosion. A webGIS-based decision support system (DSS) was developed to provide complete information on soil erosion in the Guder watershed forming a part of the Abay River Basin in Ethiopia. The parameters employed were estimated using remote sensing data. Sub-watersheds were prioritised based on soil erosion risk through a revised universal soil loss equation (RUSLE) integrated with geographic information system (GIS). The study employed high-resolution spatial data, including rainfall, soil properties, and topography, to model erosion rates across the watershed. Results indicate that the annual soil loss in the watershed varied significantly from 0 to 8021 t ha⁻¹ yr⁻¹, with an average loss of 97.5 t ha⁻¹ yr⁻¹. About 33.3% of the watershed experienced very high soil loss (&gt;50 t ha⁻¹ yr⁻¹), accounting for 91.3% of the total eroded. In contrast, 25.5% of the area exhibited medium soil erosion rates (&lt;5 t ha⁻¹ yr⁻¹). The WebGIS tool developed is powerful and user-friendly portal that enables non-technical users to access real-time soil erosion data and better understand soil conservation programs, helping them identify measures to reduce soil erosion in the watershed. Moreover, this information also supports land managers, policymakers, and farmers in adopting targeted soil erosion control measures, promoting sustainable land management in the region.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 2","pages":"Article 100387"},"PeriodicalIF":0.0,"publicationDate":"2025-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143783527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Petrogenesis and tectonic setting of Neoarchean K-rich granitoids in the Zhulagou area: Implications for the crustal maturation of Yinshan Block, western North China Craton","authors":"Xiao Wang ,&nbsp;Jin Liu ,&nbsp;Hai Zhou ,&nbsp;Xiaoguang Liu ,&nbsp;Chenying Yu ,&nbsp;Shuhui Zhang ,&nbsp;Jian Zhang","doi":"10.1016/j.geogeo.2025.100384","DOIUrl":"10.1016/j.geogeo.2025.100384","url":null,"abstract":"<div><div>K-rich granitoids are considered as an indicator of the maturation of the continental crust, particularly in correlation to the significant crustal evolution during the Neoarchean Eon. The Yinshan Block, a typical Neoarchean microcontinental block of the western North China Craton (NCC), preserves several typical K-rich granites (monzogranitic gneisses). However, their petrogenesis and tectonic background of these remain unclear, hindering our understanding of the late Neoarchean crustal evolution of the NCC. This study presents new geochronological, geochemical, and Sr-Nd-Pb-Hf isotopic data on the K-rich granites exposed in the Zhulagou area, a key exposure of the Yinshan Block. Zircon U–Pb dating results suggest that the K-rich granites were emplaced at 2.52–2.50 Ga. The K-rich granites exhibit high SiO₂ (68.70–74.10 wt. %) and K₂O (3.40–7.79 wt. %) and lower MgO (0.24–1.04 wt. %) content. They also have high Sr/Y and (La/Yb)_N ratios, as well as low Y and Yb contents. Furthermore, they display variable <em>ε</em>_Hf(<em>t</em>) (–1.1 to +2.5) and <em>ε</em>_Nd(<em>t</em>) (–6.05 to +1.64) values, with relatively low Pb isotopes (²⁰⁶Pb/²⁰⁴Pb_(t) = (13.910485–15.241164), ²⁰⁷Pb/²⁰⁴Pb_(t) = (14.806723–15.259938), and ²⁰⁸Pb/²⁰⁴Pb_(t) = (33.758621–35.592727)), indicating that their parental magmas may have originated from the partial melting of a thickened lower crust with heterogeneous sources. Combined with previous data, we suggest that a pulse or stage of mantle plume may have been operating under the Yinshan Block during late Neoarchean period. The pre-existing thickened (mafic) lower crust was partially melted to generate these K-rich granites at 2.52–2.50 Ga, resulting in a mature and stable continental crust.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 2","pages":"Article 100384"},"PeriodicalIF":0.0,"publicationDate":"2025-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143783526","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Redox conditions, solute sources and biogeochemical cycling in the Orosirian ocean: Geochemical and isotopic evidence from stromatolitic carbonates of ∼1.9 Ga Tadpatri Formation, Cuddapah Basin, India","authors":"M. Ashok,&nbsp;Nurul Absar","doi":"10.1016/j.geogeo.2025.100386","DOIUrl":"10.1016/j.geogeo.2025.100386","url":null,"abstract":"<div><div>The Orosirian Period of the middle Paleoproterozoic Era was marked by a decline in atmospheric oxygen and a reducing ocean after a brief oxidized interval of the preceding Great Oxidation Event. Here, we present C<img>O, Nd-Sr isotopic and trace element geochemistry of ∼1.9 Ga stromatolitic Tadpatri Carbonates (TC) to understand the redox condition, solute sources and carbon cycling in the Orosirian ocean. The stromatolite morphology shows deposition under inter-tidal to sub-tidal shallow marine conditions. Varying degrees of dolomitization of low-Mg calcites by an Mg-rich and ¹³C-depleted saline marine fluid at elevated temperature (140–200ºC) and high fluid-to-rock ratios (50–200) significantly modified the depositional C<img>O isotopic composition, and δ¹³C values (–1.5‰ - –2‰) recorded in low-Mg calcite are likely closest to the depositional values. These carbon isotopic values are significantly lower compared to the global Orosirian records. Low U/Th, V/<em>Sc</em>, and Mo/<em>Sc</em> in TC suggest a small seawater inventory of redox-sensitive elements, and in conjunction with high Fe-, Mn- concentrations and absence of Ce-anomaly indicates an anoxic- ferruginous ocean. High radiogenic εNd_1.9Ga values (–5.6 - –3.9) of TC compared to the older Dharwar Craton (–9.6) suggest solute sources from a juvenile crust or mantle-derived hydrothermal fluids. Very high U/Th and V/<em>Sc</em> in the Lower Vempalle Formation suggest oxidized conditions at ca. 1999 Ma, and progressive upward decrease of U/Th and V/<em>Sc</em> in the Middle-, Upper-Vempalle and Tadpatri Formations to much lower levels indicate a drawdown in atmospheric <em>p</em>O₂ level.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 3","pages":"Article 100386"},"PeriodicalIF":0.0,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143850686","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mapping of hematite ore deposits using multi-sensor data in the Sekota District, Northern Ethiopia","authors":"Jerbaw Tiruneh Abejehu ,&nbsp;Binyam Tesfaw Hailu ,&nbsp;Worash Getaneh ,&nbsp;Karuturi Venkata Suryabhagavan","doi":"10.1016/j.geogeo.2025.100385","DOIUrl":"10.1016/j.geogeo.2025.100385","url":null,"abstract":"<div><div>Iron plays a vital role in fueling the economic development and technological advancement of a country. Despite Ethiopia, being endowed with a large amount of iron ore resources in different parts of the country, prospective zones are not delineated properly. Therefore, this study aims to identify the iron ore prospective zones in the Sekota district of Ethiopia utilizing ASTER and Sentinel−2A satellite data for further onsite exploration and testing. In addition, powder diffraction analysis (XRD) was conducted to determine the dominant mineralogical phases. The image processing techniques such as ASTER band 2/band 1 (ASB2/B1) and Sentinel−2A band 4/band 2 (S2B4/B2) band ratios, principal component analysis (PCA), and subpixel level mapping technique, mixture-tuned matched filtering (MTMF) were used to map the distribution of hematite. ASB2/B1 and S2B4/B2 band ratios mapped hematite iron ore covering an area of 102.50 and 97. 68 km². The selected PC4 of ASTER delineated hematite mineralized zones covering 133.40 km² and Sentinel 2 PC3 of 110.70 km² area. A very high spectral feature fit was found between the extracted hematite endmember and USGS resampled hematite spectra. The spectral fit of the endmember was 0.74 for ASTER and 0.86 for Sentinel−2. Hematite anomaly zones were identified with MTMF using these endmembers in different parts of the study area. Powder X-ray diffraction analysis (XRD) revealed high hematite phases ranging from 36.8%−85.5% of Fe₂O₃. A strong positive correlation was found between S2B4/B2 and S2B4/B2 (<em>r</em> = 0.83), ASB2/B1 and ASTER PC4 (<em>r</em> = 0.94). Moderate correlations for ASB2/B2, S2B4/B2 (<em>r</em> = 0.44), PCA (<em>r</em> = 0.44), ASTER and Sentinel−2 MTMF (<em>r</em> = 0.36). Results of both datasets show comparable areal coverage and overlay with three of the existing known iron occurrence polygons. Thus, it is evident that techniques employed are effective in narrowing hematite anomalies zones for further onsite gological exploration.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 2","pages":"Article 100385"},"PeriodicalIF":0.0,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143776390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Introduction: Special Issue on critical metals for clean energy transition","authors":"Jie Zhou ,&nbsp;David I. Groves","doi":"10.1016/j.geogeo.2025.100382","DOIUrl":"10.1016/j.geogeo.2025.100382","url":null,"abstract":"","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 2","pages":"Article 100382"},"PeriodicalIF":0.0,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143739192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Source-to-sink history of detrital garnet from coastal dune sands in SW Mexico","authors":"Lizeth Carlos Delgado ,&nbsp;Juan J. Kasper-Zubillaga ,&nbsp;Raymundo G. Martínez-Serrano ,&nbsp;Mayumy Amparo Cabrera Ramírez ,&nbsp;Elsa Arellano-Torres ,&nbsp;José Luis Sánchez Zavala","doi":"10.1016/j.geogeo.2025.100381","DOIUrl":"10.1016/j.geogeo.2025.100381","url":null,"abstract":"<div><div>A morphological and geochemical study of detrital garnet was conducted to assess its utility in understanding sedimentary processes in coastal dune sands caused by in a weathering-limited erosion regime along the southwestern coast of Mexico. Multiple analytical techniques helped to elucidate the garnet's provenance, shape modification and surface alteration during its source-to-sink sedimentary dispersal. A Wavelength Dispersive Spectrometry (WDS) in an Electron Microprobe Analyzer (EMPA) (n = 89) revealed the dominance of almandine as the main mineral type related to the ortho-paragneiss source rocks from the Oaxacan Complex with a lesser contribution from the Xolapa Complex, outcropping in northwestern of the coastal dune sands. Scanning Electron Microscopy (SEM) helped to assess the compactness and convexity of shape descriptors by contouring the outline of detrital garnet (n = 200) and to identify the microtextures of the mineral's surface. A Raman Spectroscopy (n = 17) was employed to determine the presence of hydroxide or oxyhydroxide coatings to quantify the chemical weathering degree caused by steady and shallow burial conditions. Results show that the detrital garnet mainly underwent aeolian abrasion followed by fluvial subaqueous and marine controls. The former was supported by the quantification of moderate to high compactness and convexity values and the SEM observation of aeolian mechanical microtextures like bulbous edges, adhering particles and abrasion fatigue compared to the subaqueous microtextures as large conchoidal fractures (&gt;50 µm). Finally, we found that low to moderate chemical dissolution control modified the detrital garnet's surficial texture, evidenced by chemical microtextures like solution pits, etch pits, etch features, imbricate wedge marks and mound features. Hence, detrital garnet dissolution was dominated by its chemical composition, the nonstoichiometric character of the dissolution rate and its crystallographic forms.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 2","pages":"Article 100381"},"PeriodicalIF":0.0,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143739193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Biotite as a petrogenetic discriminator in the polymetamorphosed rocks: A case study from the Champaner supracrustal rocks, Western India","authors":"Parita K. Gorania ,&nbsp;Gayatri N. Akolkar ,&nbsp;Aditya U. Joshi ,&nbsp;Manoj A. Limaye ,&nbsp;Mahendra K. Singh","doi":"10.1016/j.geogeo.2025.100380","DOIUrl":"10.1016/j.geogeo.2025.100380","url":null,"abstract":"<div><div>The mineral chemistry of Fe-Mg biotite has served as an aid to the petrogenesis of igneous rocks, especially for identifying the parent magma compositions. Though the interpretation of igneous and metamorphic processes utilizing biotite mineral chemistry is not upfront, it certainly provides preliminary insights into the petrogenetic characteristics of rocks. Apart from thermometry and chronology, studies emphasizing on the significance of biotite mineral chemistry for unveiling the protolith compositions, grade of metamorphism, origin, and P-T conditions of metamorphic rocks are poorly documented in the literature. Here we employ biotite mineral chemical compositions i.e., EPMA (electron probe micro-analyzer) data from the metapelitic rocks of the Meso-Neoproterozoic Champaner Group, exposed as an arcuate fold belt in western India to unravel the metamorphic rock record. This group of rocks display a complex deformational and polymetamorphic history, evident in distinct mineral assemblages that reflect regional, contact, and combined regional-contact metamorphism. The field observations, mesoscopic features of rocks, reaction textures, and biotite petrographic characteristics have revealed three distinct varieties of metapelitic rocks i.e., phyllites, spotted phyllites, and hornfelses. The mineral chemistry and cation substitution mechanisms of biotite selected from phyllite, spotted phyllite and hornfels suggests, the chemical composition of biotite in these rocks is a function of the bulk rock composition, co-existing minerals, type, and grade of metamorphism and thereby attesting to the pressure-temperature conditions of rock. Further, various compositional classification diagrams and Ti-in biotite thermometry demosntrate an increase in the grade of metamorphism from west to east of Champaner Group with intermittent as well as late-stage plutonic felsic intrusions. Thus, biotite being frequently the dominant or sometimes even sole Fe-Mg mineral with temperature-pressure driven substitutions in low-grade metamorphic rocks can offer a unique opportunity to unlock valuable insights into their metamorphic history.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 2","pages":"Article 100380"},"PeriodicalIF":0.0,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143715357","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}